Google already went public with a detailed schedule of the Google I/O 2016 technical sessions. But what will be revealed in the opening two-hour keynote led by Google CEO Sundar Pichai is a tightly held secret until May 18 at 10 a.m. PT. The following are some rumors and educated guesses about what Google could announce during the keynote. 1. Augmented reality (AR), virtual reality (VR) and 360° video announcements. Google probably won’t announce a VR headset. Not because Google can’t, but because developers’ attention is completely consumed by the Oculus and the HTC Vive maelstrom and because 50 different VR headsets are predicted to be announced at the Consumer Electronics Show (CES) next January. Headsets will become a commodity that doesn’t fit Google’s business model—though it may sell one…